ndisc: Add missing strategies for per-device retrans timer/reachable time settings.

Noticed from Al Viro <viro@ftp.linux.org.uk> via David Miller
<davem@davemloft.net>.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index a55fc05b..282fdb3 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1727,10 +1727,10 @@
 	return ret;
 }
 
-static int ndisc_ifinfo_sysctl_strategy(ctl_table *ctl, int __user *name,
-					int nlen, void __user *oldval,
-					size_t __user *oldlenp,
-					void __user *newval, size_t newlen)
+int ndisc_ifinfo_sysctl_strategy(ctl_table *ctl, int __user *name,
+				 int nlen, void __user *oldval,
+				 size_t __user *oldlenp,
+				 void __user *newval, size_t newlen)
 {
 	struct net_device *dev = ctl->extra1;
 	struct inet6_dev *idev;